A variety of materials and structural arrangements, as well as processing techniques for their manufacture, have heretofore been used or proposed for use for producing acoustical and trim acoustical panels of a type adapted to be installed against the interior surfaces of structural panels, defining the passenger compartment of automotive vehicles or the like. Such panels have been effective in reducing the transmission of engine and road noise into the passenger compartment and in some instances, have also been employed to further enhance the aesthetic decor of the passenger compartment by the application of suitable finishes to the exposed face of the panel. The important considerations heretofore associated in the manufacture and use of such panels has been the cost of the material itself, the cost of its manufacture and the ease by which such panels can be installed at selected locations adjacent to the structural panels defining the vehicle body. A further important consideration has been the acoustical property of such panels and their durability over prolonged service during which they are subjected to wide variations in ambient conditions.
Composite, contoured sound insulating panels which have been commercially acceptable typically comprise a fibrous pad having a dense filled resinous or asphaltic coating applied substantially uniformly on at least one face surface thereof. Prior art processes typically employed for manufacturing such composite sound insulating panels are disclosed in U.S. Pat. Nos. 3,429,728; 3,536,557 and 4,035,215. In accordance with the foregoing patented processes, fibrous panels are molded to impart a preselected shape-sustaining contour thereto and are coated with a dense sound insulating substance, such as a highly filled asphaltic or bituminous base material, or alternatively, a highly filled thermoplastic resinous material such as a plastisol, for example. The composite structure of such panels has contributed to a significant reduction in the noise level of passenger compartments of automotive vehicles.
The energy crisis has prompted an increased emphasis on the manufacture of more fuel efficient automobiles and reductions in the size and weight are important considerations in attaining this goal. In the selection of lighter weight materials and structural components to achieve a reduction in the weight of the vehicle, careful consideration has been given to the maintenance of passenger safety and comfort. There, accordingly, has developed a need for an improved acoustical and trim acoustical panel which is of lighter weight, but which nevertheless provides for satisfactory sound and thermal insulating characteristics, which is of economical manufacture, which is simple to install and which provides for versatility in its use at selected locations in automobile bodies or the like.
The present invention provides for an improved acoustical trim panel as well as for novel methods of producing such trim panels on a commercial scale at economical cost, whereby sound insulating characteristics are retained at a substantial reduction in weight of such panels.